openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/fs/smb/client/smb1debug.c b/fs/smb/client/smb1debug.c
new file mode 100644
index 000000000..e2d013e75
--- /dev/null
+++ b/fs/smb/client/smb1debug.c
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ *   Copyright (C) International Business Machines  Corp., 2000,2005
+ *
+ *   Modified by Steve French (sfrench@us.ibm.com)
+ */
+#include "cifsproto.h"
+#include "smb1proto.h"
+#include "cifs_debug.h"
+
+void cifs_dump_detail(void *buf, size_t buf_len, struct TCP_Server_Info *server)
+{
+#ifdef CONFIG_CIFS_DEBUG2
+	struct smb_hdr *smb = buf;
+
+	cifs_dbg(VFS, "Cmd: %d Err: 0x%x Flags: 0x%x Flgs2: 0x%x Mid: %d Pid: %d Wct: %d\n",
+		 smb->Command, smb->Status.CifsError, smb->Flags,
+		 smb->Flags2, smb->Mid, smb->Pid, smb->WordCount);
+	if (!server->ops->check_message(buf, buf_len, server->total_read, server)) {
+		cifs_dbg(VFS, "smb buf %p len %u\n", smb,
+			 server->ops->calc_smb_size(smb));
+	}
+#endif /* CONFIG_CIFS_DEBUG2 */
+}